Whoever have guessed?

You approach Rainham Marshes through a dystopian world with dozens of large lorries thundering past decrepit industrial units complete with power lines overhead. This must be one of the grimiest areas of London, the dust and fumes pervades everywhere.

Turning into the Reserve one wonders if the journey was worth it.

[T]hen everything changes, described as a vital green lung for the Thames corridor, suddenly all you can hear is birdsong. This was a day spent with my grandson recently. The weather held the promise of rain in the air and a strong wind. It didn’t matter the little lad was fascinated.

This ancient medieval grazing marsh bordering the mighty River Thames on the Essex borders was a Ministry of Defence firing range for nearly 100 years up until 1996 which inadvertently saved it from development. The RSPB have spent since 2000 restoring this vital green lung for the Thames corridor to its former glory. It now holds the biggest flocks of wintering dabbling duck, godwits and Curlew in the London area and is one of the easiest places to catch up with some of London’s scarcer birds.

The visitors’ centre is manned by friendly volunteers offering advice and refreshments with plenty of activities for little ones. While views through the huge picture windows offer a landscape of huge skies and the panoramic sight of the Marsh with the abundant wildlife as the Thames wide and slow moving drifts by, with the Queen Elizabeth II Crossing in the distance.

Wheelchair access and clean well-built hides gave my grandson his first opportunity to see nature up close: water fowl, water vole and grazing cattle. With the Thames estuary along its southern flank giving a glimpse seabirds.

This is the last stretch of ancient riverside marshland inside the M25. Little has changed on this medieval freshwater march since its original reclamation from the salty Thames. A perfect day out from the hustle and bustle of London.